Genes

FEATURED ARTICLES ABOUT GENES - PAGE 2

A new and perhaps final report from the international consortium of laboratories that decoded the human genome has revised the estimated number of human genes sharply downward. About 20,000 human genes have been identified, and up to 5,000 more may await discovery, the group is reporting today in the journal Nature. This shrinking tally is considerably fewer than the 30,000 or so predicted by the consortium and its commercial rival, Celera, when they first described their draft genome sequences in February 2001.

Gray hair, wrinkled skin and the other hallmarks of old age all may be caused by a few dozen critical, age-addled genes, according to a new report by scientists who tracked gene activity over the course of a lifetime. The work reveals promising targets for medicines that might forestall many aspects of old age. Surprisingly, it also suggests that some medicines already on the market for certain diseases may be inadvertently speeding or slowing the general aging process. More generally, the research gives a tantalizing glimpse of the kinds of studies that are becoming possible with the recent advent of "gene chips," DNA-coated microchips the size of a postage stamp.

A woman's vulnerability to bulimia nervosa, an eating disorder, is largely inherited through her genes, according to a Virginia Commonwealth University study of twins. The VCU researchers concluded that bulimia nervosa is about 80 percent inherited, even though parental and environmental influences can also play a role. Previous research had shown that the disorder runs in families, but the relative importance of genes, parenting and social influences was unclear. Bulimia nervosa is a disorder in which people go through a cycle of binge eating and purging through self-induced vomiting or use of laxatives or diuretics.

Researchers have found the locations of at least five genes that are associated with insulin-dependent diabetes, and they say that people who inherit particular combinations of these genes are extremely likely to develop the disease. It is the first solid proof that diabetes is caused by several genes acting in concert, said Dr. Kathleen Wishner, president of the American Diabetes Association, and a discovery that may have practical consequences in the not too distant future. "It's very exciting news," said Ken Farber, executive director of the Juvenile Diabetes Foundation International in New York City, a group that financed the new research.

Your sense of humor has nothing to do with your genes, and everything to do with your upbringing, according to a new finding by biologists in London. They were surprised to find that whether you love or hate Gary Larson cartoons depends on the way you were raised. Genes don't seem to shape appreciation of this kind of humor at all. Most personality traits, such as being a shrinking violet or the life and soul of the party, are at least partly determined by your genes, so researchers suspected the same applies to our sense of humor.

Life on Earth did not start just once, as biology books have long taught, but possibly millions of times. Most of these experiments of nature failed, but three managed to beg, borrow or steal enough genes from the losers to hang on. In fact, if rambunctious prelife bundles of chemicals hadn't cooperated 3.8 billion to 4.5 billion years ago and exchanged primitive genes on a wholesale basis, thereby sharing newly invented survival skills, life would probably...

Between 9,000 years ago and 5,000 years ago, the practice of farming spread across a Europe inhabited by bands of hunter-gatherers. As agriculture moved from what is now Turkey and swept to the west and the north, Europe became densely settled with farming villages. Archaeologists have long debated how that happened. Many experts have cited cultural transmission. They say farming was passed along by learning, as one hunter-gatherer taught his gardening skills to his neighbor. Once the hunter-gatherers got the hang of farming, the thinking goes, they settled down and their populations exploded.

Heredity has a lot to do with your chances of living to 100, according to a study of Massachusetts centenarians. But if your family is not blessed with extreme longevity, the chances of reaching an advanced age depend largely on the person, not on the genes. The study found that brothers and sisters of centenarians have four to five times the likelihood of living into their nineties, compared with siblings of people who died at age 73. "If most of your relatives have died around or before the average U.S. life expectancy _ about 76 right now _ alarm bells should be going off, because you probably don't have the genes to get you to very old age in good health," said Dr. Thomas Perls, director of the New England Centenarian Study.

Scientists have long puzzled over how humans and chimpanzees can share 98.7 percent of the same genes, yet have vastly different mental capacities. Now an international team of researchers says it knows why. The genes in human brains, they report in the Thursday issue of Science, operate in different ways than the ones in chimps do, potentially giving humans a huge lead in mental prowess over their closest primate relative. The brain appears to be the only organ where gene function varies so dramatically between humans and chimps, the researchers said.

Researchers have deciphered the complete genetic code of rice, accelerating efforts to improve a staple that feeds half the world, an international consortium led by Japan announced Wednesday. Humanity has been growing rice for 10,000 years but only now, after scientists have dissected the molecules of its creation, can the farmers who raised 880 billion pounds of rice last year directly manipulate the blueprint of its growth and development. In all, there are 120,000 varieties of rice, but just two of them -- japonica and indica -- supply 20 percent of the world's calories, feeding more than 2 billion people in Asia alone.